After I was an undergrad pupil again in Colombia, I used to be making an attempt to determine what to do for my thesis. In Colombia—or at the least at my alma mater, Universidad Icesi—it’s necessary to finish a thesis to graduate. Throughout this time, I stumbled upon and skim three of my favourite papers: Janzen (1967), Ghalambor et al. 2006, and Muñoz et al. (2014). After studying these papers, a query popped into my thoughts: Does the identical occur within the Andes? Particularly, does chilly tolerance lower with elevation whereas warmth tolerance stays unchanged?
I shared this concept with my thesis mentors, María del Rosario Castañeda and Gustavo A. Londoño, and advised them, I need to do that! I need to take a look at how thermal limits and thermal tolerance breadth differ with elevation each inside and amongst anole species.
Lengthy story quick, I collected information on chilly and warmth tolerance for 14 anole species throughout 5 totally different websites in Colombia. Nevertheless, as a result of restrictions at Universidad Icesi, I might solely use information from 4 species for my thesis. Quick ahead to over a 12 months in the past, once I was discussing this dataset with my PhD mentor, Jonathan Losos. He stated, you need to use this information for one among your PhD chapters. So, I did. Now, it’s revealed within the Evolutionary Journal of the Linnean Society: Salazar et al. 2024.
Now, let’s speak about Colombian Andean anoles. Most of what we all know concerning the thermal physiology of anoles comes from Caribbean species. There’s a noticeable hole in details about the thermal limits of Andean-dwelling anoles. Solely a handful of papers have been revealed on this subject: Méndez-Galeano and Calderón-Espinosa 2017, Méndez-Galeano et al. 2020, Montoya-Cruz et al. 2024, and Pinzón-Barrera et al. 2024. Nevertheless, most of those give attention to a single species.
Between 2016 and 2017, a number of undergrad college students and I visited 5 totally different areas in Colombia to measure chilly and warmth tolerance in Andean anoles. We spent practically seven months within the discipline over a 12 months and a half. We measured 367 people—males, females, and juveniles—from 14 species throughout two clades: Draconura (5 species) and Dactyloa (9 species) alongside an elevation gradient (200–3000 m). Our examine addressed two key questions:
- How does thermal variation throughout elevation predict the evolution of two key physiological traits in tropical mainland ectotherms?
- How has thermal physiology advanced within the Andean radiation of anole lizards?
Earlier than diving into the outcomes, let me share some fieldwork tales. In the event you’ve ever looked for anoles within the Caribbean or the Andes, you’ll know the challenges. Earlier than my journeys, Rosario took me alongside on one among hers to show me the fundamentals. We spent a couple of days within the discipline and located a few lizards. On the time, I believed, I’ll by no means discover sufficient lizards to put in writing a thesis!
Discovering anoles within the Andes is hard. Through the day, they’re nearly inconceivable to identify, and when you do see one, catching it’s one other story. Since I not often succeeded through the day, we shifted to fieldwork at evening. Even then, in some areas we didn’t see lizards for days. To maximise information assortment, I made a decision to seize and measure each particular person I discovered and assess whether or not the lizard was large or wholesome sufficient to be measured.
Strolling via the evening within the Colombian Andes; Parque Nacional Pure Tatamá – 2000m,. The anole I’ve in my hand is an Anolis princeps, my favourite species.
Right here’s a aspect story: Rosario as soon as advised me how totally different it was to catch anoles within the Caribbean. She stated it’s simpler to see and catch them there, and you’ll even determine on the spot which one to measure. I didn’t imagine her—till I joined Kristin Winchell within the Dominican Republic. I had by no means seen so many anoles in a single place—it was unbelievable! Nonetheless, I like trying to find anoles within the Andes, although it’s tougher. I’m unsure why, however the Andes will at all times maintain a particular place in my coronary heart—possibly it’s as a result of one among my discipline websites is simply half-hour from my mother and father’ home, most likely I’ll by no means know haha.
What did we discover? As anticipated, we discovered that chilly tolerance (CTmin) and warmth tolerance (CTmax) improve with environmental and operative temperatures however lower with elevation. Nevertheless, opposite to what different research have reported, warmth tolerance doesn’t stay unchanged with elevation. Not like their Caribbean counterparts, Andean anoles don’t seem to make use of behavioral buffering to restrict divergence in warmth tolerance throughout elevations—a phenomenon generally known as the Bogert impact (Muñoz et al. 2022). It’s attainable that Andean anoles don’t thermoregulate behaviorally in the identical manner Caribbean species do, although this nonetheless requires additional investigation (however see Méndez-Galeano and Calderón-Espinosa 2017).
We additionally discovered that chilly and warmth tolerance advanced at comparable charges. Phylogenetic evaluation revealed that thermal limits can differ amongst carefully associated species, difficult the thought of area of interest conservatism and pointing to flexibility in physiological tolerance as species diversified alongside elevation gradients. As well as, the Andes’ complicated geography performed a major position in driving the variety of thermal physiology inside these anoles. Understanding how physiological range influences species diversification might make clear how two clades from the identical genus, with distinct evolutionary histories, exhibit comparable responses to adapting to mountainous environments. Our information on Andean anoles are per this attitude: whether or not close to sea stage or a number of kilometers above it, species are physiologically specialised to their native thermal situations, and exhibit comparatively slender tolerance breadth, as predicted for tropical lizards (Huey et al. 2009).
To reply these two questions:
- How does thermal variation throughout elevation predict the evolution of two key physiological traits in tropical mainland ectotherms? Chilly and warmth tolerance decreases with elevation.
- How has thermal physiology advanced within the Andean radiation of anole lizards? Each traits evolve at comparable fee, however their evolution is unbiased of the phylogeny.
In a quickly warming world, the essential query is whether or not these species can hold tempo with the accelerating impacts of local weather change on their pure environments. Future analysis ought to give attention to understanding how rising temperatures and shifting rainfall patterns will affect the exercise patterns, vitality steadiness, and inhabitants progress charges of Andean anoles. By linking physiological variation to demographic traits, we will higher predict how these exceptional lizards may fare beneath the pressures of world change.
I hope this examine sparks curiosity to additional discover Andean anoles—and even Amazonian anoles, which stay surprisingly understudied.
One final aspect story—I’m unsure what number of of you’ve seen this image, however I took that stunning shot of Anolis chloris throughout one among my discipline journeys as an undergrad.
References:
Salazar JC, Londoño GA, Muñoz MM, et al. The Andes are a driver of physiological range in Anolis lizards, Evolutionary Journal of the Linnean Society 2025; 4(1): kzae040. https://doi.org/10.1093/evolinnean/kzae040
Ghalambor CK, Huey RB, Martin PR, et al. Are mountain passes greater within the tropics? Janzen’s speculation revisited, Integrative and Comparative Biology 2006; 46: 5-17. https://doi.org/10.1093/icb/icj003
Janzen DH. Why mountain passes are greater within the tropics, The American Naturalist 1967; 101: 233-249. https://www.jstor.org/secure/2458977
Méndez-Galeano MA, Calderón-Espinosa ML. Thermoregulation within the Andean lizard Anolis heterodermus (Squamata: Dactyloidae) at excessive elevation within the Jap Cordillera of Colombia, Iheringia, Série Zoologia 2017; 107: e2017018. https://doi.org/10.1590/1678-4766e2017018
Méndez-Galeano MA, Paternima-Cruz RF, Calderón-Espinosa ML. The very best kingdom of Anolis: Thermal biology of the Andean lizard Anolis heterodermus (Squamata: Dactyloidae) over an elevational gradient within the Jap Cordillera of Colombia, Journal of Thermal Biology 2020; 89: 102498. https://doi.org/10.1016/j.jtherbio.2019.102498
Montoya-Cruz A, Díaz-Flórez RA, Carvajalino-Fernández JM. Thermal steadiness in Andean lizards: A perspective from the excessive mountains, Austral Ecology 2024; 49: 313578. https://doi.org/10.1111/aec.13578
Muñoz MM, Stimola MA, Algar AC, et al. Evolutionary stasis and lability in thermal physiology in a bunch of tropical lizards, Proceedings of the Royal Society B 2014; 281: 20132433. https://doi.org/10.1098/rspb.2013.2433
Muñoz MM. The Bogert impact, a consider evolution, Evolution 2022; 76: 49-66. https://doi.org/10.1111/evo.14388
Pinzón-Barrera C, Suárez-Ayala N, Carrillo-Chávez LM, et al. Unveiling essential thermal limits of Anolis tolimensis (Squamata, Anolidae) throughout an elevational panorama, Present Herpetology 2024; 43: 155-134. https://doi.org/10.5358/hsj.43.115
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